Hand-drawn physics objects in AndEngine

I found that "Chalk Ball has been developed with andengine and Box2D as physics engine".

Chalk ball is a physics game. You can draw a line by your finger and it will be 开发者_高级运维a physics object. How can I make such effect? Do I need to use particle systems to create custom curve lines? And how can I build them like physics objects? Or it will be a polygon with many points?

I asked developer of the ChalkBall about the method and he answered:

"It is a sequence of Rectangles, but I am warning you in advance, AndEngine has quite some flaws and weirdness. Not sure of which version you are using, but the one of January is quite defective and I had to do many workarounds."